Communications Connector with Improved Contacts

ABSTRACT

A network cable jack includes a printed circuit board (PCB) for balancing both inductive and capacitive coupling. Using a PCB allows compact trace paths to be formed without significantly increasing manufacturing costs. By including on each trace path two distinct inductance zones separated by a neutral zone, significant gains in degrees of freedom are achieved for designing PCB trace patterns in which a pair of inductive coupling zones jointly offset the inductive coupling caused by a specification plug and the jack contacts, both in magnitude and phase angle. Further, using distinct inductance zones offers more freedom regarding the placement of capacitive plates for use in capacitance balancing as well as the placement of terminals and insulation displacement contacts. Although the magnitude of a capacitive coupling is determined by the length of the capacitor plates parallel to current carrying traces, the approach allows capacitive and inductive coupling to be balanced independently.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/788,916, filed May 27, 2010, which is a continuation of U.S. patentapplication Ser. No. 11/670,668, filed Feb. 2, 2007, which issued asU.S. Pat. No. 7,726,018 on Jun. 1, 2010, which is a continuation of U.S.patent application Ser. No. 11/014,097, filed on Dec. 15, 2004, whichissued as U.S. Pat. No. 7,182,649 on Feb. 27, 2007, which claimedpriority to U.S. Provisional Application No. 60/531,756, filed on Dec.22, 2003, the subject matter of which is hereby incorporated byreference in their entireties. Further, this application incorporates byreference in its entirety U.S. Pat. No. 5,997,358, entitled “ElectricalConnector Having Time-Delayed Signal Compensation,” filed on Sep. 2,1997, as well as all materials incorporated therein by reference.

BACKGROUND

The invention is directed generally to an electrical connector and morespecifically to an electrical connector having improved inductive andcapacitive coupling balancing characteristics.

It has long been desired to improve the electrical performance ofparticular components or whole systems by minimizing crosstalk therein.There is a reduction in both near end crosstalk (NEXT) and far endcrosstalk (FEXT) when both the net inductive and capacitive crosstalkcomponents are reduced in magnitude.

Past efforts to minimize the inductive component of crosstalk have insome cases included altering the length and orientation of the connectorcontacts to provide offsetting inductive coupling to preexistinginductive coupling present in the plug or elsewhere in the connector.However, the manufacturing processes required to produce contacts havingspecial lengths and orientation are expensive. In addition, suchcontacts have been relatively long which causes excessive phase shift athigh frequency. In addition, the inductance between such contacts aresubject to excess variability. In addition or instead of such contactdesigns, past efforts to minimize crosstalk utilizing phase-offsettingcoupling between pairs on a printed circuit board (PCB) have primarilyutilized capacitive coupling. As such, better ways of balancing bothinductive and capacitive coupling thereby minimizing crosstalk aresought.

SUMMARY

The inventive connector and printed circuit board (PCB) provides aninductance-balancing function with traces on the PCB. It is synergisticin that it utilizes the inductive balancing traces to provide acapacitive-balancing function. This provides advantages over previousdesigns in terms of ability and cost to achieve a desired result with acompact connector. It also provides greater design flexibility andimproved performance.

In some preferred embodiments of the invention, there is provided a jackfor receiving a compatibly configured standard plug that terminates fourtwisted wire pairs. The jack includes a PCB having eight contactsprojecting from a front side thereof for mating with the plug, eightinsulation displacement contacts (IDC's) projecting from a rear sidethereof, and eight traces embedded in the printed circuit boardconnecting corresponding terminals and IDC's (numbered 1-8 to facilitatereference). Four traces on the PCB are selectively routed in variouszones thereof to create two distinct zones of coupling separated by arelatively coupling-free neutral zone. The introduced couplings improvethe overall performance of pairs 3,6 and 4,5 of the combination of thejack and the plug.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded front upper right perspective view of a jack inaccordance with an embodiment of the invention;

FIG. 2 is a rear upper right perspective view of the jack of FIG. 1;

FIG. 3 is a front elevational view of the jack of FIG. 1 in assembledform;

FIG. 4 is a cross-sectional view of the jack of FIG. 3 taken across theline A-A in FIG. 3;

FIG. 5 is a cross-sectional view of the jack of FIG. 3 taken across theline B-B in FIG. 3;

FIG. 6 is a front elevational view of the jack of FIG. 1 with acooperative plug inserted therein;

FIG. 7 is a cross-sectional view of the jack of FIG. 6 taken across theline C-C in FIG. 6;

FIG. 8 is a schematic front elevational view of the layout of thecurrent carrying traces of a printed circuit board in accordance with anembodiment of the invention;

FIG. 9 a is a schematic cross-sectional view of the printed circuitboard of FIG. 8 taken across the line A-A in FIG. 8;

FIG. 9 b is a schematic cross-sectional view of the printed circuitboard of FIG. 8 taken across the line C-C in FIG. 8;

FIG. 9 c is a schematic cross-sectional view of the printed circuitboard of FIG. 8 taken across the line E-E in FIG. 8

FIG. 10 is a schematic front elevational view of the printed circuitboard of FIG. 8 showing inductive zone partitions and inductive vectororigin locations;

FIG. 11 is a schematic vector diagram showing inductive magnitudes andphase angles in accordance with a preferred embodiment of the invention;

FIGS. 12 a and 12 b shows the addition of capacitor plates to a sectionof current carrying traces of the PCB shown in FIG. 8;

FIG. 13 is a schematic front elevational view of the layout of the PCBshown in FIG. 8 with the addition of capacitor plates;

FIGS. 14 a, 14 b, and 14 c are schematic cross-sectional views of thePCB of FIG. 13 taken across the lines A-A, B-B and C-C in FIG. 13;

FIGS. 15 a and 15 b are perspective views of a jack like thatillustrated in FIG. 1 except the cable termination cap has been replacedwith permanent punchdown blocks which are used for a punchdown cabletermination method;

FIGS. 16 a and 16 b are exploded perspective views of the jack of FIG.14;

FIG. 17 is a cross-sectional view of the jack of FIG. 16 taken acrossthe line A-A in FIG. 16 b;

FIG. 18 is a side view of the contacts and contact holder of the jack ofFIG. 6;

FIG. 19 is a perspective view of an alternate design of one of theoutside contacts of FIG. 18;

FIGS. 20 a and 20 b are schematic drawings of the contact of FIG. 19;

FIG. 21 is an exploded perspective view from the rear of the rearportion of the jack of FIG. 1 including the metal pair divider;

FIG. 22 is an exploded perspective view from the front of the rearportion of the jack of FIG. 1 including the metal pair divider;

FIG. 23 is a side cross-sectional view of the metal pair dividerinstalled in the rear portion of the jack of FIG. 1;

FIG. 24 is an exploded perspective view from the rear of the rearportion of a shielded version of the jack including the metal pairdivider;

FIG. 25 is an exploded perspective view from the front of the rearportion of a shielded version of the jack including the metal pairdivider;

FIG. 26 is a side cross-sectional view of the metal pair dividerinstalled in the rear portion of a shielded version of the jack of FIG.1;

FIG. 27 is a perspective view of a shielded version of the jack of FIG.1;

FIG. 28 is an exploded view of the jack of FIG. 27;

FIGS. 29 a and 29 b are perspective views of an alternate design of agrounding cap for the jack of FIG. 27;

FIGS. 30 a and 30 b are end and side views of the grounding cap of FIG.29;

FIG. 31 is a front perspective view of a “shielded patch panel” for usewith the shielded jack of FIG. 27;

FIG. 32 is a rear perspective view of a “shielded patch panel” of FIG.31;

FIG. 33 is an exploded perspective view of the “shielded patch panel” ofFIG. 31;

FIGS. 34 a and 34 b are side cross-sectional views of the “shieldedpatch panel” of FIG. 31;

DETAILED DESCRIPTION OF EMBODIMENTS

FIGS. 1-7 show a connector that may utilize a coupling balancing circuitboard in accordance with the invention. From front to back in theexploded views (FIGS. 1 and 2), there are a main housing 1 and a contactcarrier 2 for supporting eight contacts 3 thereon. The contactspreferably engage a PCB 4 from the front in through-hole style, as doeight IDCs 5 from the rear. A rear housing 6 preferably having a pair ofguide rails 7 includes passageways for the IDCs, and a wiring cap 12 maypreferably include a quartered electrically conductive pair divider 10for isolating individual wire pairs therein. Unshielded twisted pairs ofwires in this area typically have a variable amount of twist which isdependent on the manual installation process. Shielded twisted pairs ofwires in this area typically have a variable amount of shield which isdependent on the manual installation process. The divider eliminatescrosstalk coupling between the wire pairs in this area. The divider 10may include a mounting post 11 for mounting the divider within theconnector, such as into a keyhole slot 9. A latch 8 may be used forassembling the rear housing 6 and the wiring cap 12.

FIGS. 8 and 9 show the PCB traces between correspondingly numberedcontact holes and IDC holes, wherein specific trace cross-sectionallayouts are shown within the compensation zone (FIG. 9 a), the neutralzone (FIG. 9 b), and the crosstalk zone (FIG. 9 c). As a result of thesecross-sectional trace designs, inductive coupling is purposefullyintroduced between particular wire pairs within the compensation andcrosstalk zones, while the neutral zone is generally free ofpurposefully introduced coupling.

FIG. 10 schematically shows trace-length zone partitions and/ormidpoints to establish inductance vector origin points for calculatingnet inductive coupling (vector addition based on magnitudes and phaseangles of particular inductive coupling zones). FIG. 11 is a schematicvector diagram showing inductive coupling magnitudes and phase anglesnetting to zero for the particular jack embodiment shown.

Using a PCB to provide inductance balancing is preferable to someconventional inductance balancing techniques (such as contactorientation) in that trace paths on a PCB are compact and inexpensive toattain without incurring significantly increased manufacturing costs.Additionally, using only a single compensation zone, where inductance ofa certain magnitude (path length as the paths run in parallel) ispurposefully introduced to offset a predetermined inductance from a plugor other portion of the connector is ineffective at high frequencies dueto phase shift. The inventive connector utilizes the teachings of U.S.Pat. No. 5,997,358 to take phase shift into account. This applicationincorporates by reference in its entirety U.S. Pat. No. 5,997,358. Byincluding two distinct inductance zones, however, separated by a neutralzone, one realizes significant gains in degrees of freedom for designingtrace patterns on a PCB so that the pair of inductive coupling zonesjointly offset the inductive coupling caused by a specification plug andthe jack contacts both in magnitude and phase angle.

In a preferred embodiment of the invention, an electrical path mayextend from the plug through the portion of a contact between the plugcontact point and the contact through-hole on the PCB, along aprecompensation portion of a trace, into a compensation zone of thetrace, into a neutral zone of the trace, into a crosstalk zone of thetrace, and into a corresponding IDC. Particular traces are run closelytogether in the compensation and crosstalk zones so as to introduceinductive coupling between particular trace pairs in these zones, whilethe precompensation zone and neutral zone are generally devoid of anyintentionally introduced inductive coupling between trace pairs. Thelengths of the various trace portions are subject to designconsiderations but are generally chosen to provide path lengths withinthe various zones so that the inductive coupling provided by thecompensation and crosstalk zones and their locations combine togenerally offset the inductive couplings in the plug and jack contacts.

Although there are several degrees of freedom in designing this system,the inclusion of the neutral zone, in particular, between the twoinductance zones (the compensation zone and the crosstalk zone), yieldsconsiderable freedom in designing the through-hole locations and tracepaths on the PCB, and thus offers more freedom pertaining to where theterminals and IDC's may be located on the PCB. It also provides moreoptions for the introduction of capacitance on the PCB so that it alsoserves a capacitance balancing function.

In a preferred embodiment as shown in FIG. 10, the printed circuit boarddesign taught herein has three zones of inductive coupling between pairs3,6 and 4,5. There is a compensation zone (zone b) and a crosstalk zone(zone c) and the magnitude of these couplings can be adjusted by thelength of the zones. There is also a neutral zone which has minimal netcoupling between pairs and its length can be adjusted.

FIG. 11 is a vector simulation of this embodiment.

The vectors in FIG. 11 simulate the following:

Vector a: The crosstalk of the plug and the crosstalk of the jackcontacts with their phase shift relative to the center (inductivecoupling center) of the compensation zone.

Vector b: The compensation of the printed circuit board compensationzone, the b vector, is all effectively located at the center of thiszone.

Vector c: The crosstalk of the printed circuit board crosstalk zoneadjusted for the crosstalk of the IDC's, the c vector, is alleffectively located at the center of this zone with their phase shiftrelative to the center of the compensation zone.

The phase shift due to the distance and environment between b & c isequal to the phase shift due to distance and environment between a & b.As seen in FIG. 11, with this design, ∠ab=∠bc, the length of vector aequals the length of vector c and the vertical component of vector aplus the vertical component of vector c equals the length of vector b ata Null Frequency of 500 MHz. The ideal results, as illustratedschematically by FIG. 11, can be attained by the independent adjustmentof ∠bc by adjusting the length of the Neutral Zone and by adjusting themagnitudes of vectors b & c.

The objectives of the design of the jack as shown in FIG. 1 with a PCBas shown in FIG. 13 is to compensate for the crosstalk between pairs 3,6and 4,5 of a specification Cat. 6 plug caused by both inductive andcapacitive coupling.

The current carrying traces on the PCB provide capacitive coupling inthe compensation and crosstalk zones which is similar to the inductivecoupling which they provide, however, additional capacitive coupling isrequired. This is provided by selectively adding capacitor plates aboveand below sections of current carrying leads as shown in FIGS. 12-14.

FIGS. 12 a and 12 b shows the addition of capacitor plates to a sectionof current carrying traces of the PCB shown in FIG. 8.

FIG. 13 is a schematic front elevational view of the layout of the PCBshown in FIG. 8 with the addition of capacitor plates.

FIG. 14 is a schematic cross-sectional view of the PCB of FIG. 13 takenacross the line A-A in FIG. 13.

This design provides relatively compact PCB geometry. It utilizescurrent carrying traces to provide the required inductive and capacitivecoupling in both the compensation and crosstalk zones.

The location of each capacitive coupling is controlled by the locationof the connection between a current carrying trace and the associatedcapacitor plates. The magnitude of each capacitive coupling isdetermined by the length of the capacitor plates parallel to the currentcarrying traces.

The capacitive coupling vector origin locations are proximate theinductive coupling vector origins, however, the inductive and capacitivecouplings are independently balanced.

The couplings of the specification plug have been calculated as follows:

Inductive Coupling: 1.428 nH

Capacitive Coupling: .936 pF

The design parameter objectives of the jack PCB design are:

Zone Zone Length Inductive Coupling Capacitive Coupling Compensation.297″  3.09 nH 1.812 pF Neutral .250″ 0 0 Crosstalk .176″ 1.830 nH 1.046pF Vector Angle AB = Vector Angle BC = 32.36°

This design was determined by simulation and calculation and is thebasis for the design of a prototype. To tune the prototype, a plot ofNEXT dB vs. frequency should be run. First, the length of the neutralzone should be varied until the Null (−dB) is maximized. Assuming thatthe magnitude of vector a equals the magnitude of vector b, this willmake ∠ab equal to ∠bc. Second, the magnitude of the compensation zoneshould be varied until the Null frequency is 500 MHz. If the length ofthe compensation zone is varied to vary its magnitude, the length of theneutral zone must also be varied to make <ab equal to <bc. It should benoted that the crosstalk and compensation provided by the PCB will be acombination of inductive and capacitive coupling and the idealcombination will match the combination of a standard plug and the jackcontacts.

The teachings taught herein can also be applied to additional paircombinations. State of the art methods would be used to obtain optimumpair impedance and balance to neutral of each pair.

The same PC board will also accommodate the IDC's for a punchdowntermination design as illustrated in FIGS. 15-17.

FIGS. 15 a and 15 b are perspective views of a jack which is similar tothat shown in FIG. 1, however, the wiring cap 12 has been replaced withpunchdown termination blocks 13.

The main housing 1 is substantially the same as the jack shown in FIG.1.

FIGS. 16 a and 16 b are exploded perspective views of the jack shown inFIGS. 15 a and 15 b.

The stems of the IDC's 14 are the same as those of the jack of FIG. 1,however, the locations and orientations of the IDC blades 15 have beenaltered. In this manner, preferred IDC blade locations and orientationsare attained for both a wiring cap and punchdown blocks with a commonPCB.

FIG. 17 is a cross-sectional view of the jack of FIG. 16 taken acrossthe line A-A in FIG. 16 b.

FIG. 18 shows one embodiment of jack contacts 16 and contact holder 17.The construction of the contacts and contact holder maintains thecontacts in the contact holder before and after assembly of the contactholder into the jack housing. In this embodiment, all the odd numberedjack contacts 16 o have one unique shape. The even numbered jackcontacts 16 e have another unique shape and all contacts have uniquecross-section dimensions, to provide the required contact force with arelatively short conductive path from an installed plug to the printedcircuit board, without permanent deformation of contacts.

In addition, the contact holder 17 incorporates a radiused support 18under each contact 16 which reduces stress concentration in eachcontact.

The contact shape is relatively horizontal in the section 19 thatcontacts the plug to minimize the change in contact force due toallowable dimensional variations in specification plugs.

The ratio of contact width to contact thickness is approximately 1.8:1.This ratio for typical state of the art rectangular contacts is 1.3:1.The free ends of the contacts 20 are supported.

If a six contact plug were installed in a jack with the above contacts,contacts number one and eight would be damaged. To prevent this,protrusion keys 21 in FIG. 1 are included in the jack housing in thecontact number one and eight locations which prevent the installation ofa six contact plug.

In another embodiment as shown in FIG. 19, contact 22 has an alternatedesign to facilitate installation of a six position plug without contactdamage. A contact 22 is installed in the number 1 and 8 contactposition. This contact design includes a unique “safety pin” loop 23which electrically contacts itself where the contact is adjacent toitself at 24 to provide a short conductive path between the plug and thePCB coupled with mechanical flexibility.

FIGS. 20 a and 20 b are schematic drawings of the contact of FIG. 19.The “safety pin” loop 23 is constrained in the contact holder 17 andtwisted as shown by the arrows to insure electrical contact at 24 toprovide current path 26.

The contact 22 of FIG. 19 is designed to minimize the length of theconductive path from the plug to the printed circuit board and inaddition to survive the installation of a six contact plug in the eightcontact jack.

As shown in FIGS. 21-26, there is a metal pair divider 10 which isinstalled in the jack in the factory. In the field, the cable isinstalled in the cap 12 and the cap is pressed into the opening 28 inthe back 6 of the jack, terminating the cable and locating the metalpair divider adjacent to the end of the cable.

As shown in FIG. 23, the metal pair divider 10 provides an electricalshield between wire pairs in the area 28 near the end of an installedcable. This portion of the cable typically lacks proper twist of thewires of each pair and/or lacks proper shielding of each pair.

The metal pair divider 10 therefore decreases crosstalk magnitude andvariation.

When the cap is installed, there is a space 29 between the end 30 of themetal pair divider 10 and an installed cable jacket which is sufficientto facilitate the necessary reorientation of pairs between the cablejacket and the IDCs.

FIGS. 21-23 show the rear portion of the non-shielded jack of FIG. 1.

FIGS. 24-26 show the rear portion of a shielded version of the jack ofFIG. 1.

The difference in the shielded version is the replacement of wiring cap12 with shielded wiring cap 31 shown on FIG. 26 which consists of aplastic portion 32 shown on FIGS. 23-26 and a metal portion 33 shown onFIG. 26.

FIG. 27 is a perspective view of a shielded version 34 of the jack ofFIG. 1.

FIG. 28 is an exploded view of the jack of FIG. 27 showing the shield35, the main housing 1, the rear housing 6, the pair divider 10 and theshielded wiring cap 31.

FIGS. 29 a and 29 b are perspective views of an alternate design of themetal portion 33 of the shielded wiring cap 31.

FIGS. 30 a and 30 b are end and side views of the metal portion 33 ofcap 31.

The design of the shielded versions eliminates the need to install theshield in the field. When the cable is installed in the cap, the cableshield is connected to the metal portion of the cap.

When the cap is installed in the jack body, the metal portion 33 of thewiring cap 31 is connected to the jack shield.

This strain relief/grounding cap assembly provides a means to secure ashielded cable to a jack and to electrically connect the shield of aninstalled cable to the shield of the jack. This design accommodates alarge range of cable diameters.

Installation of the strain relief/grounding cap assembly:

1. Cable is prepared per the following instructions:

-   -   remove jacket, 1 ½″-2″    -   fold back the braid over the jacket—wrap excess around jacket    -   locate pairs per cap/conductor orientation (e.g. 568B)

2. Conductor pairs are fed through the grounding cap and oriented, foilshields are cut off where each wire will enter wire slot, wires are bent90 degrees, inserted in wire slots, and cut off.

3. Cap assembly is located in the back of the jack housing and pressedin with an installation tool or pliers (not shown).

4. The spring clip is fully engaged with a pliers or the like to ensuregood contact between the braid of the cable and the grounding cap.

5. The ground is connected from the cable/overbraid by clip/groundingcap to spring tabs on the housing shield.

FIGS. 31 is a perspective front view of a “shielded patch panel” 36 foruse with a shielded jack such as shown in FIG. 27.

FIG. 32 is a perspective rear view of the patch panel 36 shown in FIG.31.

FIG. 33 is an exploded perspective rear view of the patch panel 36.

The components include a metal frame 37, plastic inserts 38, springmetal grounding strip 39 with grounding fingers 40 a means to ground thestrip 39 to the network ground 41 (not shown).

FIG. 34 a is a side cross-sectional view of the patch panel 36.

FIG. 34 b is a side cross-sectional view of the patch panel 36 with atypical shielded jack 26 installed with a grounding finger 40 pressingagainst the jack shield 35 at location 41.

1. A communications connector comprising: a housing, the housing havingan opening; and a plurality of contacts wherein at least one contact ofthe plurality of contacts has a portion that forms a safety pin loop. 2.The communications connector of claim 1 wherein the at least one contactcontacts itself at a point in the loop where the at least one contact isadjacent to itself.
 3. The connector of claim 2 further comprising acontact holder, the contact holder configured to retain the portion ofthe at least one contact that forms a safety pin loop.
 4. The connectorof claim 3 wherein the plurality of contacts comprises eight contactsgenerally aligned in a single row such that the contacts can besequentially numbered from 1 to 8 starting at a first end and ending atan opposite end and further wherein the first and the eighth contacts ofthe plurality of contacts have a safety pin loop.